The present invention concerns design of filters for electrical circuits and pertains particularly to an analog sampling filter.
A filter rejects some frequencies within a signal and allows other frequencies to be transmitted. In a low-pass filter the frequencies which are transmitted extend from zero to some maximum frequency. In a high-pass filter the frequencies which are transmitted are greater than some minimum frequency. In a band-pass filter, the frequencies which are transmitted are between a minimum frequency and a maximum frequency. In a notch filter, a very narrow range of frequencies is removed from the signal.
There are many ways to construct filters. Generally, when designing filters it is desirable to very particularly pass only desired frequencies while as completely as possible rejecting other frequencies. Generally filters which are very effective at passing desired frequencies and rejecting other frequencies are difficult to design and expensive to build. The present invention sets out filters which are elegant in design, inexpensive to build and extremely effective.